Pollutant Powerplay

FROM THE DECEMBER ISSUE: Ener-Core’s power oxidation system draws energy from volatile organic compounds to produce heat and power, offsetting natural gas use.

By Lisa Gibson | November 16, 2017

Historically, whenever a country passes new rules on air quality, it means many of its industries will need to pump more money into pollution abatement, says Alain Castro, CEO of Ener-Core Inc. But Ener-Core has a gamechanger, he says. “The paradigm shift that’s happening with us is that we’re one of the few solutions coming out that is going the opposite way—the tighter the emissions compliance gets, we can help companies get lower costs while becoming lower-emissions producers of whatever their product is, in this case, ethanol.”

Pacific Ethanol in Stockton, California, will be the first ethanol plant to use Ener-Core’s Power Oxidizer, a combined-heat-and-power plant fueled by waste gas, using volatile organic compounds as fuel. The unique technology allows destruction of the VOCs, while making use of their energy content, says Guillermo Gomez, lead applications engineer for the company.

But the benefits don’t stop there. “You’re allowing them to produce more ethanol from the benefit of being far below the emission regulations,” Gomez adds. “That’s really the name of the game.”

How it WorksA typical gas turbine has limited space for residence time—the time it takes for the fuel to react in a reaction zone, Gomez says. That means the fuel, methane for instance, makes its initial and rapid conversion to carbon monoxide and other products of incomplete combustion, but does not have ample time to then make its more time-consuming conversion to carbon dioxide and water, he says. But the Power Oxidizer uses a larger vessel, allowing longer residence time and turbulence for almost complete conversion of the fuel to carbon dioxide and water.

No flame and a larger vessel mean a near-perfect reaction with low emissions, less than 1 part per million for NOx, which is lower than any permit Castro has seen anywhere in the world, he says. “We’re different from the pollution status quo,” he says, adding the system exceeds regulatory compliance levels, and does it in a financially productive manner.

“We can consume and use low-quality fuels like VOCs to actually, not just prevent them from becoming an emission, but actually use them to do something productive, which is generate energy.” Instead of running waste gas VOCs through a regenerative thermal oxidizer, the plant can produce electricity, steam and heat, perhaps even shutting down the RTO.

In some applications, the Power Oxidizer can produce sufficient energy from VOCs alone, but that is not the case at Pacific Ethanol, Gomez says. Supplemental natural gas is used, so the main financial and carbon offset benefit is from the production of steam, he adds. “Our power oxidizer is able to produce close to 30,000 pounds of steam to offset their steam production by approximately half. They can use less natural gas-fired boilers and, hence, this reduces their carbon footprint and greatly increased the project economics.”

The DriverCastro says the goal at Pacific Ethanol, whose executives declined to be interviewed for this article, saying the technology is too new for them to be able to comment on its benefits, is to complete installation by the end of this year and produce 3.5 megawatts of energy. Castro hopes interest in the Power Oxidization system will spread in the ethanol industry, once Pacific Ethanol’s installation is up and running.

“At the end of the day, the ethanol industry is a commodity industry. Cost is king. … If you can find a way—and we have—to enable an ethanol plant to reduce its operating costs by $4 million—which is what Pacific Ethanol has said they intend to save here—while reducing their emissions, that’s really a home run.”

Gomez stresses the benefits of heat at ethanol plants for the distillers grains drying process. “Heat has an immense cost, as well.”

Ener-Core’s primary markets are the chemical, pharmaceutical, wastewater treatment and oil and gas industries, Castro says. While the Power Oxidizer does make use of pollutants, reduces carbon intensity and ensures regulatory compliance, the main driver behind customers’ choices to implement it is its financial benefit, he says. “Having a low emissions standard may prompt companies to deploy a solution like this faster … but, ultimately, the real underlying reason it’s being done is for the operational, economic benefits.”

Ethanol plants both domestically and internationally have expressed interest in the system, Castro says.

Policies at PlayThe Power Oxidizer isn’t the only option out there, and interest in it and other emissions-reduction technologies could increase with changes in regulations. Some U.S. states are initiating even stricter emissions policies than those in the Clean Air Act. California has its Low Carbon Fuel Standard, and Oregon and Washington are taking on similar initiatives.

“Given the trend towards higher credit prices in the California LCFS, as well as developing LCFS policies in other jurisdictions, there could be additional financial incentives for investment in technologies that reduce ethanol carbon intensity,” says Brendan Jordan, vice president of the Great Plains Institute. “California LCFS credit prices are currently high enough to make carbon capture and storage or utilization profitable for an ethanol plant, assuming pipeline infrastructure for carbon dioxide can be built out.”

Ernie Pollitzer, owner and senior engineer with Clean Energy Consultants, says carbon sequestration is the emissions-reduction tactic with the most potential, and the EPA is working on new regulations for it. “It is more of a guidance and it was not clear if ethanol plants could have a new pathway if they use carbon sequestration, but at least EPA is recognizing the potential for this technology.”Jordan adds that the FUTURE Act would offer a tax credit for carbon capture and storage. A Senate version of the bill has been introduced in both the House and Senate.

And across the country, about 85 ethanol plants have achieved efficient producer pathway status through the EPA, enabling them to generate RINs for production volumes above those grandfathered under the RFS, provided they meet the 20 percent greenhouse gas (GHG) reduction threshold. Ethanol plants have taken multiple measures to improve pollution abatement, and their tactics and technologies have evolved with the industry. Vendors have improved thermal oxidation burners and CO2 scrubbers, Pollitzer says, and many plants have invested in CHP.

Castro says Ener-Core’s Power Oxidizer CHP system only becomes more beneficial as policies become stricter. “Most pollution abatement today is an insurance tool. You use it to get your emissions down to stay within compliance. It’s seen as a cost center. It’s not seen as a profit center to the operations. We’re achieving a lot: We’re generating power and heat and steam onsite with no NOx and using VOCs as a source of energy.”